2017 ASHRAE Annual Conference

When modeling an HVAC system using fan powered terminal units with EnergyPlus, the user must enter values for fan total pressure rise and fan/motor efficiency. A recent study found that for an 8 inch inlet (203 mm) series fan powered terminal unit, the fan total pressure was considerably lower than values commonly recommended in online training sources. Values in that study were on the order of 0.25 in. w.g. (63 Pa) and not 1.5 or even as much as 3 in. w.g. (374 – 747 Pa). Manufacturer’s performance data were used to verify and extend VAV fan powered terminal unit total pressure rise measurements as determined in a previous study.

The current version of ASHRAE Standard 170 procludes natural ventilation in all spaces in healthcare facilities. This work-group suggests it should be allowed in most healthcare spaces, except for Operating Rooms, Procedure Suites, Sterile Core areas, Interventional Radiology or Cardiology Spaces, Airborne Isolation Areas, and Protective Environments. Natural or mixed-mode ventilation designs may offer some benefits. Among the most likely are energy reduction and enhanced occupant satisfaction. Less likely benefits may include enhanced indoor air quality and a more beneficial microbiome. When considering natural ventilation in health care, designers must fully address the fundamental challenges of space appropriateness, climate appropriateness, acoustics, security, and outdoor air quality. Projects implementing natural ventilation should anticipate commissioning challenges.

The energy consumption of the heating and cooling coils of the air handling units of an educational building with multiple laboratories has been evaluated and suitable energy recovery methods were assessed in an attempt to reuse the energy lost in the exhaust air stream and promote energy conservation while complying with the current building codes. The HVAC system of Life Sciences II (LS II) building of Southern Illinois University Carbondale, is a constant air volume (CAV), 100% outside air (OA) system due to the many laboratories in the building. It is one of the most energy intensive buildings on campus.

The adoption of energy efficient standards significantly cut the energy consumption in buildings by reducing envelope heat transfer and internal heat gain. These energy efficiency measures reduce not only the electrical load but also the cooling load as well as the supply airflow rate. As a result, additional reheat is typically required to maintain the minimum airflow setpoint under partial space cooling loads for conventional air handling units (AHUs) and may degrade the effectiveness of energy efficient measures. The AHUs with return air bypass (RAB) provides an alternative to reduce additional reheating and overcooling at the minimum airflow rate with good space humidity control. The purpose of this paper is to investigate the energy and control performance of the AHUs with RAB under different operating conditions through simulations.